Probability of sequences can be calculated by multiplying the chance of the first event by the chance of the second, and so on.
The probability of tossing a coin and getting heads is 50%, or 0.5, and the probability of selecting a number less than four from 1-10 is 40%, or 0.4.
The overall probability can then be expressed as:
0.5 x 0.4 = 0.2 or 20%
There is a twenty percent chance that a heads would be tossed and a number less than four selected.